Post-exercise ketosis and the glycogen content of liver and muscle in rats on a high carbohydrate diet

Summary Post-exercise ketosis is known to be suppressed by physical training and by a high carbohydrate diet. As a result it has often been presumed, but not proven, that the development of post-exercise ketosis is closely related to the glycogen content of the liver. We therefore studied the effect of 1 h of treadmill running on the blood 3-hydroxybutyrate and liver and muscle glycogen concentrations of carbohydrate-loaded trained (n=72) and untrained rats (n=72). Resting liver and muscle glycogen levels were 25%–30% higher in the trained than in the untrained animals. The resting 3-hydroxybutyrate concentrations of both groups of rats were very low: <0.08 mmol·1⁻¹. Exercise did not significantly influence the blood 3-hydroxybutyrate concentrations of trained rats, but caused a marked post-exercise ketosis (1.40±0.40 mmol·1⁻¹ 1 h after exercise) in the untrained animals, the time-course of which was the approximate inverse of the changes in liver glycogen concentration. Interpreting the results in the light of similar data obtained after a normal and low carbohydrate diet it has been concluded that trained animals probably owe their relative resistance to post-exercise ketosis to their higher liver glycogen concentrations as well as to greater peripheral stores of mobilizable carbohydrate.     

Examination of the Short-Term Efficacy of a Parent-Based Intervention to Prevent Skin Cancer

The research evaluated an intervention strategy designed to prevent skin cancer in young adolescents. The intervention used parents as change agents to effectively communicate the risks of skin cancer and encourage their children to avoid high-risk sun-related behaviors while increasing positive sun-safe behaviors. Three hundred and forty parents in two regions of the United States were educated about the dangers of risky sun behaviors and how to convey information about skin cancer prevention to their children. Parents were then encouraged to talk with their children about these issues over a 1-month period prior to the onset of summer. Following this time period, children whose parents received and implemented the intervention materials were compared with a control sample of 129 children. These two groups were matched on age, gender, and school on number of sunburns and sunburn severity, attitudes and beliefs, and sunbathing behavior. Children in the treatment condition differed significantly from controls in the predicted directions on all outcome variables. The findings are discussed in terms of reducing skin cancer risk behaviors of children via parent-based intervention approaches.     

Vaccination with streptococcal extracellular cysteine protease (interleukin-1β convertase) protects mice against challenge with heterologous group A streptococci

Virtually all clinical isolates of group A streptococci secrete a highly conserved extracellular cysteine protease that cleaves human fibronectin and vitronectin, and converts IL-1β precursor to biologically active IL-1β. Based on the high degree of gene conservation within the species and its role in host pathogenicity, it was postulated that antibodies to the cysteine protease would confer protective immunity against S. pyogenes infection. To test this hypothesis, Swiss CD1 mice were intraperitoneally administered either saline, rabbit IgG, or IgG from rabbits immunized with the protease, and challenged with a highly virulent (minimum lethal dose 10 cfu) clinical isolate of S. pyogenes expressing a heterologous cysteine protease. The results indicate that mice administered IgG from rabbits immunized with purified cysteine protease had significantly enhanced survival when compared with mice given either non-specific rabbit IgG (log rank test; χ²; p = 0.0195) or saline (log rank test; χ²; p = 0.0002). Moreover, mice actively immunized with the cysteine protease had a significantly longer time to death than the control group (log rank test; χ²; p = 0.0418). The results show that the cysteine protease elicits non-type-specific immunity to challenge with heterologous S. pyogenes.     

Plant virus transmission by plasmodiophorid fungi is associated with distinctive transmembrane regions of virus-encoded proteins

Summary.  Computer analysis of published sequence data has consistently identified two complementary transmembrane domains in the coat protein readthrough domains of benyviruses, furoviruses and pomoviruses and in the P2 proteins of bymoviruses. These viruses differ in genome organisation but are all transmitted by plasmodiophorid fungi. The second domain is absent or disrupted in naturally-occurring deletion mutants that cannot be fungally-transmitted. In a non-transmissible substitution mutant of Beet necrotic yellow vein virus [Tamada et al. (1996) J Gen Virol 77: 1359–1367], the alignment of the helices is disrupted. From conserved patterns detected in transmembrane helix sequences and calculated relative helix tilts, structural arrangements consistent with tight packing of transmembrane helices were identified. These included ridge/groove arrangements between the two helices and strong electrostatic associations at the interfacial regions of the membrane. The data strongly suggest that these transmembrane helices facilitate the movement of virus particles across the fungal membrane. Accepted November 9, 2000 Received June 30, 2000     

The Effects of Discrimination Training on Voluntary Control of Cephalic Vasomotor Activity

The present study was conducted to test Brener's calibration theory of visceral learning. It was hypothesized that training in discrimination of cephalic vasomotor responses would enhance acquisition of voluntary and biofeedback control of cephalic vasomotor response. Four groups were given discrimination training to detect either constriction, dilation, both constriction and dilation, or given false feedback. All groups were then given biofeedback training in constriction. All groups were assessed on discrimination accuracy, acquisition of biofeedback control of constriction, and voluntary control of dilation and constriction. The results indicated that discrimination of cephalic vasomotor responses can be learned and that this skill facilitates the acquisition of biofeedback and voluntary control of vasomotor responses. This facilitation occurs only if discrimination training is given for the specific response to be learned. The data suggest that discrimination of the relevant response is a necessary but not sufficient condition for acquisition of voluntary control in biofeedback learning.     

Problems affecting performance of the fluorescent treponemal antibody-absorption test for syphilis.

Immunofluorescent staining of Treponema pallidum was studied to clarify the effect of three factors on the results of the fluorescent treponemal antibody-absorption test: (i) heat inactivation of sera at 56 degrees C for 30 min before testing, (ii) use of multicircle slides, and (iii) tungsten illumination to visualize and assess unstained treponemes on reactive as well as nonreactive smears. It was found that serum inactivation before testing was not necessary for detection of immunoglobin G antibody, but an immunoglobulin M prozone was detected in unheated serum. On multicircle slides, it was demonstrated that a false-positive reaction could be obtained in 30 s at 37 and 25 degrees C if a smear where a nonreactive serum had been placed was crossed by a strongly reactive serum from another circle. Tungsten illumination proved necessary for correct assessment of unstained treponemes on all fluorescent treponemal antibody-aborption test smears, reactive or nonreactive. The possible role of these factors in incorrect fluorescent treponemal antibody-absorption test results is discussed.     

Lack of alpha-adrenoreceptor binding of [125I]BE2254 to rat basilar artery membranes

Rat basilar arteries do not contain classical alpha- or beta-adrenoreceptors as assessed by electrophysiological techniques even though these arteries are innervated by catecholamine-containing perivascular nerves. These arteries were therefore examined for their ability to selectively bind an alpha-adrenoceptor radioligand, [125I]BE2254 (2/beta/4-hydroxyphenyl)-ethylaminomethyl)-tetralone). For comparison, rat tail arteries were also studied as these are known to contain functional alpha-adrenoreceptors. It was found that basilar artery membranes had only one-third of the specific binding of tail artery membranes and this finding collaborates the electrophysiological data.     

Dominant mutations affecting both sporulation and sterigmatocystin biosynthesis in Aspergillus nidulans

The initiation of conidiophore development in the filamentous fungus Aspergillus nidulans is a complex process requiring the activities of several genes including fluG, flbA, flbB, flbC, flbD, and flbE. Recessive mutations in any one of these genes result in greatly reduced expression of the brlA developmental regulatory gene and a colony morphology described as fluffy. These fluffy mutants have somewhat diverse phenotypes but generally grow as undifferentiated masses of vegetative hyphae to form large cotton-like colonies. In this paper we describe a genetic screen to identify dominant mutations resulting in similar fluffy colony morphologies. We have identified 36 dominant fluffy mutant strains and shown that 29 of these mutants have greatly reduced brlA expression as compared to wild-type. In addition, we have found that 19 of these mutants are not only developmentally altered but also fail to produce the toxic, carcinogenic, secondary metabolite sterigmatocystin. At least three of the mutants isolated result from dominant activating mutations in fadA which encodes the Gα subunit of a heterotrimeric G-protein. Another of the mutants results from a dominant interfering mutation in brlA. We discuss the approaches taken to characterize these potentially important regulators of growth, development and secondary metabolism. Received: 13 February / 28 May 1997